The structure and biosynthesis of epidermal growth factor precursor

Scott, James; Patterson, Sian T.; Rall, Leslie B.; Bell, Graeme I.; Crawford, Robert J.; Penschow, Jennifer D.; Niall, Hugh D.; Coghlan, John P.

doi:10.1242/jcs.1985.supplement_3.3

Cited by 46 publications

(20 citation statements)

References 13 publications

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“…In all tissues of the body, except for the granular cells of the submandibular gland, the EGF family of growth factors are present as membrane bound precursors (Scott et al, 1985;Marechal et al, 1996). To be available for stimulating proliferation, these growth factors would be released from the cellular source when stimulated by activation of G protein-linked receptors.…”

Section: Discussionmentioning

confidence: 99%

Presence of EGF growth factor ligands and their effects on cultured rat conjunctival goblet cell proliferation

Chen

Shatos

et al. 2008

Experimental Eye Research

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The amount of mucin on the ocular surface is regulated by the rate of mucin synthesis, mucin secretion, and the number of goblet cells. We have previously shown that cholinergic agonists are potent stimuli of mucin secretion. In contrast, there have been no studies on the control of goblet cell proliferation. In this study we investigate the presence of the EGF family of growth factors and their receptors in rat conjunctiva and cultured rat conjunctival goblet cells as well as their effects on activation of signaling intermediates and goblet cell proliferation. Rat conjunctival goblet cells were grown in organ culture and identified as goblet cells by their morphology and positive staining for the lectin UEA-1 and cytokeratin 7. In the rat conjunctiva, the presence of the EGF family members epidermal growth factor (EGF), transforming growth factor α (TGF-α), heparin binding EGF (HB-EGF), and heregulin was determined by RT-PCR. The receptors for these ligands, EGF receptor (EGFR), erbB2, erbB3, and erbB4 were detected in both rat conjunctiva and goblet cells by Western blot analysis. Immunofluorescence microscopy of conjunctival tissue determined that EGFR was present as punctate staining in the cytoplasm of conjunctival goblet cells while ErbB2 was present in the basolateral and lateral membranes of goblet cells. ErbB3 was localized to the cytosol of rat conjunctival goblet cells. In cultured goblet cells, EGFR and ErbB2 were present in the perinuclear area of the cells. ErbB3 was widely distributed throughout the cytoplasm of the cells. ErbB4 was not detected in either the conjunctiva or goblet cells by immunofluorescence microscopy. Using a multiplex assay system we measured phosphorylation (activation) of p44/p42 mitogen-activated protein kinase (MAPK), also known as ERK, Jun N-terminal kinase (JNK), p38 MAPK and AKT (also known as protein kinase B), molecules known to be activated by EGF receptor members. EGF, TGF-α and HB-EGF activated the signaling intermediate proteins whereas heregulin did not. No EGF family member significantly activated AKT. Consistent with these findings, EGF, TGF-α and HB-EGF each stimulated goblet cell proliferation as measured by WST-1 assay or immunofluorescence microscopy using an antibody against Ki-67, a protein expressed in dividing cells. Heregulin did not cause goblet cell proliferation. We conclude that multiple members of the EGF family, EGF, TGF-α and HB-EGF, and heregulin are present with three of the four erbB receptor subtypes. EGF, TGF-α and HB-EGF all stimulated the activation of signaling intermediates and caused goblet cell proliferation.

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Section: Discussionmentioning

confidence: 99%

Presence of EGF growth factor ligands and their effects on cultured rat conjunctival goblet cell proliferation

Chen

Shatos

et al. 2008

Experimental Eye Research

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“…In rodents submaxillary glands, the precursor molecule is not detectable and only the mature and diffusible 6 kDa form of EGF accumulates in the secretory granules of the regulated exocrine secretory pathway (12,32,33). In this case, the release of EGF in the biological fluid (saliva) involves exocytosis, i.e.…”

Section: Epidermal Growth Factor (Egf)mentioning

confidence: 99%

Regulated Cell Surface Pro-EGF Ectodomain Shedding Is a Zinc Metalloprotease-dependent Process

Gall

Auger

Dreux

et al. 2003

Journal of Biological Chemistry

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Epidermal growth factor receptor (EGFR) ligands are synthesized as type I membrane protein precursors exposed at the cell surface. Shedding of the ectodomain of these proteins is the way cells regulate the equilibrium between cell-associated and diffusible forms of these growth factors. Whereas the regulated shedding of transforming growth factor-␣, HB-EGF, and amphiregulin precursors have been clearly established, regulation of full-length pro-EGF shedding has not been clearly demonstrated. Here, using both wild-type and M2 mutant CHO-K1 as well as HeLa cell lines transiently transfected with epitope-tagged rat pro-EGF expression plasmid, we demonstrate that these cells synthesize EGF as a high molecular weight membrane-associated precursor glycoprotein expressed at the cell surface. All cell lines are able to release the entire ectodomain of pro-EGF in the extracellular medium following juxtamembrane cleavage of the precursor once it is present at the cell surface. More significantly we clearly established that CHO-M2 and HeLa cells only constitutively release low levels of pro-EGF. This shedding is a regulated phenomenon in wild-type CHO cells where it can be induced by different agents such as phorbol 12-myristate 13-acetate (PMA), pervanadate, and serum but not by calcium ionophores. Using specific inhibitors as well as protein kinase C (PKC) depletion, PMA stimulation was shown to be completely dependent on PKC activation whereas pervanadate and serum stimulation were not. Regulated ectodomain shedding involves the activity of a zinc metalloprotease as determined by inhibition with phenantrolin and TAPI-2 and by the results obtained with the CHO-M2 shedding defective mutant cell line. Comparison of the ability of CHO and HeLa cell lines to shed pro-EGF and pro-TNF-␣ upon stimulation greatly suggests that TACE (ADAM 17) may not be the ectoprotease involved in the secretion of pro-EGF ectodomain and that this protease, which remains to be identified, shows a restricted cellular expression pattern.

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“…Pro-EGF is highly expressed in the submaxillary gland, kidney, and lacrimal gland (1). EGF is known to induce cell survival, differentiation, and proliferation (2) by binding to its membrane-bound receptors (EGFRs) (3,4).…”

mentioning

confidence: 99%

“…Thus, in the submaxillary gland, pro-EGF is fully and intracellularly processed by kallikreins into mature EGF and then stored in secretory granules (7). In contrast, in kidney, pro-EGF is found at the cell surface mainly as an unprocessed protein (1,8) or as intermediate forms generated by unknown proteases (9 -11). Among the processed forms in kidney, a prominent ϳ115-kDa membrane-bound intermediate (herein called EGF-115) was reported (12), as well as a soluble form in urine generated by an undefined serine protease (10).…”

mentioning

confidence: 99%

Proprotein Convertase PC7 Enhances the Activation of the EGF Receptor Pathway through Processing of the EGF Precursor

Rousselet¹,

Benjannet²,

Marcinkiewicz³

et al. 2011

Journal of Biological Chemistry

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Although the processing profile of the membrane-bound epidermal growth factor precursor (pro-EGF) is tissue-specific, it has not been investigated at the cellular level nor have the cognate proteinases been defined. Among the proprotein convertases (PCs), only the membrane-bound PC7, the most ancient and conserved basic amino acid-specific PC family member, induces the processing of pro-EGF into an ϳ115-kDa transmembrane form (EGF-115) at an unusual VHPR 290 2A motif. Because sitedirected mutagenesis revealed that Arg 290 is not critical, the generation of EGF-115 by PC7 is likely indirect. This was confirmed by testing a wide range of protease inhibitors, which revealed that the production of EGF-115 is most probably achieved via the activation by PC7 of a latent serine and/or cysteine protease(s). EGF-115 is more abundant at the cell surface than pro-EGF and is associated with a stronger EGF receptor (EGFR) activation, as evidenced by higher levels of phosphorylated ERK1/2. This suggests that the generation of EGF-115 represents a regulatory mechanism of juxtacrine EGFR activation. Thus, PC7 is distinct from the other PCs in its ability to enhance the activation of the cell surface EGFR.

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The structure and biosynthesis of epidermal growth factor precursor

Cited by 46 publications

References 13 publications

Presence of EGF growth factor ligands and their effects on cultured rat conjunctival goblet cell proliferation

Presence of EGF growth factor ligands and their effects on cultured rat conjunctival goblet cell proliferation

Regulated Cell Surface Pro-EGF Ectodomain Shedding Is a Zinc Metalloprotease-dependent Process

Proprotein Convertase PC7 Enhances the Activation of the EGF Receptor Pathway through Processing of the EGF Precursor

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